code: def _get_signalfname(filepath):
      """Get filenames."""
      _soft_import("defusedxml", "reading EGI MFF data")
      from defusedxml.minidom import parse
  
      listfiles = os.listdir(filepath)
      binfiles = list(
          f
          for f in listfiles
          if "signal" in f and f[-4:] == ".bin" and f[0] != "."
      )
      all_files = {}
      infofiles = list()
      for binfile in binfiles:
          bin_num_str = re.search(r"\d+", binfile).group()
          infofile = "info" + bin_num_str + ".xml"
          infofiles.append(infofile)
          infobjfile = os.path.join(filepath, infofile)
          infobj = parse(infobjfile)
          if len(infobj.getElementsByTagName("EEG")):
              signal_type = "EEG"
          elif len(infobj.getElementsByTagName("PNSData")):
              signal_type = "PNS"
          all_files[signal_type] = {
              "signal": f"signal{bin_num_str}.bin",
              "info": infofile,
          }
      if "EEG" not in all_files:
          raise FileNotFoundError(
              "Could not find any EEG data in the %d file%s found in %s:\n%s"
              % (
                  len(infofiles),
                  _pl(infofiles),
                  filepath,
                  "\n".join(infofiles),
              )
          )
      return all_files
  
file_path: mne-python/mne/io/egi/general.py
imports: import os
  import re
  import numpy
  from ...utils import _pl, _soft_import
label_desc: Use image node_id 5 for calling a global function with example usage: _get_signalfname(filepath) and returns: all_files